Folding rocking chair



April 10, 1956 J. 5. ROBERTS m 2,

FOLDING ROCKING CHAIR Filed March 2, 1953 2 Sheet-$5116 1 ATTORNEY April 10, 1956 J. s. ROBERTS 111 2,741,298

FOLDING ROCKING CHAIR Filed March 2, 1953 2 Sheets-Sheet 2 INVENTOR John S. Poberis ZZZ ATTORNEY Unite States Patent FOLDING RGCKING CHAIR John S. Roberts 111, Fairfax, Va, assignor to Trans Trading Corporation, Washington, D. C., a corporation of Delaware Application March 2, 1953, Serial No. 339,771

2 Claims. (Cl. 155-56) This invention relates to folding or collapsible chairs of the type ordinarily used on lawns, beaches, patios, etc., and is more particularly concerned with such chairs which are capable of executing a rocking motion.

Prior chairs of this general type are characteristically difiicult to open from the folded position to the proper open position. One of the principal reasons for this is the fact that the arrangement of the various pivoted members forms an unconstrained linkage with the result that when the chair is opened, the members do not consistently assume the proper position and considerable manipulation of the pivoted members is usually necessary to reset them properly. Similar difficulties for the same reasons are experienced in closing the chairs to the collapsed position.

Accordingly, one of the objects of this invention is the provision of a chair of the type mentioned which is simple and easy to open and which consistently opens to the proper position.

Another object of the invention is the provision of such a chair which is constrained to close to the proper position.

A further object of the invention is the provision of such a chair which closes to the collapsed position with a snapping action and locks the members in collapsed position under the influence of internal stresses developed in the linkage system. This feature prevents the chair from opening accidentally under normal storage conditions. For example, it can be set against a wall or fence in the collapsed position without danger of it opening under the usual forces of gravity, wind, accidental jarring, etc.

A still further object is the provision of such a chair which is sturdy and stable under normal conditions of use and which will not tip forwardly when a person is in the act of rising from or sitting in the chair.

These and other objects and advantages of the invention will be apparent from the following description considered together with the accompanying drawing.

In the drawing:

Fig. 1 is a perspective view of an embodiment of the invention in the open position.

Fig. 2 is a side elevational view of the embodimen in the open position.

Fig. 3 is a side elevational view of the embodiment in the collapsed position.

Fig. 4 is a fragmentary view, partly in section, showing one of the resilient joints of a modified form of the embodiment.

Fig. 5 is a section along the line 55 of Fig. 4.

Referring with more particularity to the drawing in which like numerals designate like parts, the embodiment illustrated comprises, generally, a rectangular back frame A and a rectangular seat frame B set in angular relation to each other and pivotally connected to each other and to a base structure C.

The back frame A in the normal open position of the ice 2 chair is inclined rearwardly and comprises a pair of parallel side members 11 and 12; a pair of spaced connecting cross bars 13 and 1 5 at the top; and a bottom connecting cross bar 15. The seat frame B is forwardly inclined and comprises a pair of spaced parallel side members 16 and 17 connected at the top by a pair of spaced cross bars 18 and 19.

The base structure comprises a pair of spaced parallel side members 20 and 21. The rearward ends of the members 20 and 21 are pivotally connected to the forward ends of links 22 and 23 by rivets or bolts 24 and 25 or other suitable pivoted connectors. The rearward ends of these links rest on the ground and are pivotally connected to the bottom of the seat frame side members 16 and 17 by similar pivotal connectors 26 and 27.

The links 22 and 23 are connected together with a cross bar 28, said cross bar underlying and acting as an abutment for rearward extensions 29 and 30 of the members 20 and 21 when the chair is in its normal open position.

The lower ends of the back frame side members 11 and 12 are pivotally connected to the side members 20 and 21, respectively, at 31 and 32. The members 20 and 21 extend forwardly a substantial distance beyond the pivot points 31 and 32 and rest on the ground.

The upper portions of the frames A and B are connected together by a group of three links on either side, namely, a horizontal link 33, a vertical link 34 and a diagonal link 35 on one side and corresponding links 36, 37 and 38, respectively, on the other side. The horizontal links 33 and 36 are in the form of arm rests for occupants of the chair and are positioned to be conveniently used for that purpose. The rearward ends of these horizontal links are pivotally connected to the back frame side members 11 and 12, as at 39 and 40, and the forward ends are provided with angle brackets 41 and 42 to which the upper ends of the vertical links 34 and 37, respectively, are pivoted by means of rivets or bolts 43 and 44- or other suitable pivotal connectors.

The lower ends of the vertical lings 34, 37 and the forward ends of the diagonal links 35, 38 are, respectively, copivoted to the seat frame side members 16, 17 by bolts 45, 46. The rearward ends of the diagonal links are pivoted to back frame side members 11 and 12 at points 47 and 48 below the pivotal connectors 39 and 40. The linkage formed by these links is such that the sum of the lengths of the diagonal and vertical links is slightly less or slightly greater than the distance between the rearward pivotal points of the horizontal and diagonal links plus the length of the horizontal link.

The back frame side members 11 and 12 are set between or inside of the bottom side members 20 and 21; the side members 20 and 21 set between the links 22 and 23, and the seat frame members 16 and 17 are on the outside of the links 22 and 23. In the normal open position of the chair, the lower cross bar 15 of the seat frame A has end extension members 49 and 50 which act as abutments for the side members 16 and 17 of the seat frame B, substantially as shown, to limit the downward movement thereof. The lower ends of the vertical links 34, 35 are disposed between their corresponding diagonal links 35, 38 and the side members 16, 17 of the seat frame 3.

A fabric body-supporting member 51 is hammocked between the upper bars 13 and 14 of the back frame A and the forward bars 18 and 19 of the seat frame B. The upper end of the fabric member 51 passes rearwardly over the top of the upper bar 13, then downwardly between the two bars 13 and 14, circles around the bottom of the lower bar 14 and is secured to an adjacent portion of the fabric member by means of snap fasteners 52 or of a person in the act of sitting in the chair or rising therefrom. The chair cannot, therefore, be tipped over without raising its center of gravity, thus establishing the condition .of stable equilibrium.

In the open position, as shown in Fig. 1, the occupant can rock himself backward and forward, the limit of forward rocking movement being fixed by the position of the extension members 49 and 50.

The folded position shown in Fig. 3 is achieved'simply by moving the upper ends of the frames A and B together. This action forces the bottom side members 20: and 21 rearwardly which acts upon the links 22 and 23 to cause them to rotate rearwardly 180 and positioning the side members 11, '12; 16, 17; and 20, 21 in substantially side by side relation, as shown in Fig. 3. However, as the members approach this folded position, the angular relation between each vertical link 34, 37 and its corresponding horizontal link 33, 36 approaches zero and the angular relation between each vertical link 34, 37 and its corresponding diagonal link 35, 38 approaches 180 or what may be considered a. dead center. Internal stresses are set up in the links due to the relative lengths of these links as explained above. Consequently, as the dead center is passed with the members in fully closed position, the internal stresses thus developed hold the members together in the collapsed position under the force of these internal stresses. In opening the chair, these internal stresses are manually overcome.

The magnitude of the internal stresses can be varied by changing the lengths of one or more of the links and/ or the distance between the pivot points 39, 40 and 47, 48 within the elastic limit of the linkages.

vThe modification, illustrated in Figs. 4 and permits an increase of the dead center throw without unduly straining the links and comprises the use of a cushioned bearing atone of the link joints of each group of links such as the joints 47, 48. The bearing comprises a hollow rubber cylinder 54 on the inside of which there is secured a metallic anti-friction band 55. The outside of they cylinder may also be provided with a metal band 56 or other suitable shield, although it is not absolutely essential. The connecting bolt 57 passes through the inner band 55. suitable washers 58 on the other side holdlthev bearing in place. By these means it may be seen that increased yieldability of the rubber cylinder makes it possible to proportion the length, of the links to provide an increase in dead center throw and this makes the locking action more positive. The term dead center throw as used herein refers to the distance between dead center and the, point at which the internal stresses begin to develop The head of the bolt on one. side and.

and is equal to the difierence between (1) the length of the. horizontal link 36 plus the distance between the joints 40 and 48, and (2) the sum of the lengths of the vertical and diagonal links 37 and 38. The latter (2) may be greater or less than the former 1) since in either case a dead center throw will be introduced with the same effect.

I claim:

1. A folding chair comprising a rectangular seat frame, a rectangular back frame, said frames being pivotally connected to a bottom base structure and extending upwardly in angular relation to each other, and a. mechanical linkage connecting said frames, said linkage consisting of a horizontal link connected to the back frame, a diagonal linkconnected, to the seat frame and to the back frame at a point below the horizontal link, and a vertical link connected to the horizontal link and the diagonal link, said linkage including a joint having a rubber bushing, the distance between the points of connection to the back frame plus the length of the horizontal link being unequal to the sum of the lengths of the vertical and diagonal links by an amount sutncient to permit an alinement of the vertical and diagonal links, horizontal links and back frame under a positive straining within the elastic limit of the linkage.

2. A folding chair comprising a rectangular seat frame, a rectangular back frame, said frames being pivotally connected to a bottom base structure and extending upwardly in angular relation to each other, and a mechanical linkage connecting said frames, said linkage consisting of a horizontal link connected to the back frame, a diagonal link connected to the seat frame and to the back frame at a point below the horizontal link, and avertical link connected to the horizontal link and the diagonal link, said linkage including a joint having a resilient bushing, the distance between the points of connection to the back frame plus the length of, the horizontal link being unequal to the sum of the lengths of the vertical and diagonal links by an amount suflicient to permit an alinement of the vertical and diagonal links, horizontal links and back frame under a positivestraining the elastic limit of the linkage.

References Cited in the file of this patent UNITED STATES PATENTS 

